Effect of gelatin, fermentation temperature, starter culture ratio on physicochemical properties of peanut kefir

Peanuts (Arachis hypogaea) are highly nutritious exerting health benefits such as preventing malnutrition, reducing heart disorders, and potentially prevent certain types of cancer. Kefir is one of the fermented dairy products containing probiotics and renowned for its beneficial effects on human health. This study aimed to evaluate the effects of gelatin concentration, fermentation temperature, and starter culture ratios on pH, the rheological properties, texture properties, and SEM (scanning electron microscope) of peanut kefir. The rheological properties of Peanut kefir exhibited pseudo plastic behavior (0 < η < 1) and weak gel properties. Peanut kefir’s rheological characteristics (viscosity, shear stress) and texture properties (hardness, adhesiveness, adhesive force) changed with gelatin content, fermentation temperature, and starter culture ratio. The FTIR spectrum of the gel peanut kefir sample was similar to that of the control sample. The optimal conditions for producing peanut kefir were 0.5% gelatin content, fermentation temperature of 25oC for 13 h, and a 5% starter culture ratio, resulting in a smooth kefir surface structure and a well-bound kefir gel. The SEM images revealed that the experimental sample exhibited a stable gel texture and no layer separation compared to the control sample. Generally, gelatin content, fermentation temperature, and starter culture ratio significantly influenced the quality of peanut kefir.